Metal composition.



METALCOMPOSITION.

APPLICATION FILED SEPT. 12| I916 1,223,002. PatentedAnr. 17.1917

NITED STATES PATENT OFFICE.

KERRY K. SANIIELL, OF CHICAGO, ILLINOIS, ASSIGNJE TO HERBERT S. MILLS,01 CHICAGO, ILLINOIS.

METAL COMPOSITION.

' a citizen of the United States, residing at 1 ing the same.

the'body do, in fact, fuse.

that the explanation of this property lies in I 221 South Green street,Chicago, in the county of Cook and State of Illinois, have invented anew and useful Improvement in' Metal Compositions, of which thefollowing is a specification. v

My invention relates to improvements in metal compositions and methodsof produc- More particularly the invention is concerned with a metallicsubstance, which may either be a single metal or an alloy, andcontaining a considerable percentage of carbon. I find that such a bodyhas peculiar properties which render it desirable for certain technicaluses.

' As is Well known, there is diificulty in obtaining satisfactoryservice from metallic contact points for opening and closing electricalcircuits. The arcing or sparking between such points proves quicklydestructive of the finished surfaces thereof, not only. volatilizing thesurfaces to cause pitting of the same but also oxidizing these surfaces,thereby increasing the contact resistance and proportionately increasingthe heating effect of the current at the contact. Through this increasedresistance and heating efl'ect further destructive pitting and oxidizingis set up. This destructive action is therefore selfperpetuating, beingin the-nature of a vicious circle, and limits the life of the contactpoints to such an extent that only a very few metals, such as platinum,and, in some'special services, tungsten, are regarded as at all servshotnickel, is introduced into the crucible iceable.

I find, however, that the commoner and less expensive metals, or alloysthereof, exhibit such properties when combined with a relatively largeproportion of carbon as to arrest the destructive action referred to.The result of such a mixture of carbon with the metal is to render themetallic body practically infusible as a body, though it is quiteprobable that the metallic constituents of It is believed the fact thatthe carbon present forms a spongy or porous mass within'the intersticesor ores of which the metal is carried and hel whether in a solid orliquid form, the outward appearance and general physical properties ofthe mass being apparently unafiected by subjection to temperatures, in

Specification of Letters Patent.

' of an electvic furnace or an oxy-aoetylene A further property of mymetal composition which renders it peculiarly valuable as a contactmetal is its resistance to oxidation under sparliing or arcingconditions. I attribute this property to the fact that the arcing orspar ing volatilizes the carbon. present to create a reducing atmospherewhich effectively prevents oxidation" of the metal of the cont actingface, Whether this metal be, in fact, in the liquid or solid state.

In order to produce a metal composition carrying a 1 elatively highpercentage of carbon, I find it advantageous to employ an apparatus ofthe form illustrated in the accompanying drawing, in which Figure 1 is aplan view of my crucible,

aperture 11 in the bar and the conductors 13 are then placed in circuitwith a suitable source of ejectric power (preferably alternating currlnt) the current is turned on and regulated in strength until the bar 10reaches a tempera-t1 re suflicient to melt the nickel.

It should be noted that the construction of the crucible is such thatthe metal therein serves as a zonductor, this condition giving rise to apeculiar phenomenon, i. 0., the molten met t1 body lyin in the bottom ofthe crucible divides itse f in the center to form separa ted pools whichcontinuously reunite and again separate. As soon as the metal isthoroughly melted I add to the Patented Apr. 1'7, 1917.

Application filed September 12, 1916. Seria I No. 119,856.

molten mas: finely divided carbon, which-I stir into thx mass as it isadded, preferably by the use of a carbon stirring-rod. I also findit ofadvantage to interrupt the current through the crucible at intervals.Within a very few minutes the molten mass within the crucible solidifiesor sets. The process is now at an end, and the current maybe turned off,the crucible permitted to cool and the block of metal compositionremoved therefrom. This block may then be machined, ground or 'otherwisefabricated to produce contact points adapted for use in any form of makeand break electrical apparatus, as, for instance, buzzers orspark-coils.

Although I prefer to stir in finely divided amorphous carbon during theheating of the metal within the crucible, this is not essential to thesuccess of the process, since I find that the crucible walls themselvesare eaten away during the process, the carbon required for thecomposition being thus supplied to a large extent by the crucibleitself.

I find that by the process above described I am able to produce a metalcomposition which appears to be homogeneous throughout its mass andwhich upon analysis shows a percentage of carbon (by weight) of from 2%to 7 per cent. in the case of nickel and nickel-iron alloys. The bestresults which I have secured have been by the use of comparatively pureshot nickel, in which I have succeeded in incorporating by this processapproximately 7 per cent. of carbon. Practically all of this carbonseems to be present as graphite, there being only traces of combmedcarbon and amorphous carbon. It appears therefore, that not only is thecarbon incorporated and homogeneously mixed in the metal, but that inthe process this carbon becomes converted into graphite.

By reference to" the table of specific gravities of metallic nickel andgraphite it appears that 7 per cent. (by wei ht) of carbon wouldrepresent a proximatefy 30 per cent. of volume or bul of thisconstituent. It appears, therefore, that my new metal compositioncontains a sufficient ercentage of graphitic carbon to distinctlydifferentiate it from any known metals or alloys.

As before stated, I have been able to secure the best results by .theuse of relatively pure nickel as a metallic constituent of mycomposition. I find, however, that a serviceable composition may beproduced by the use of a nickel-iron alloy containing upward of 70 percent. of nickel and approXi-' mately 3% per cent. ,of carbon. Mycomposition resents the general appearance of a metallic body, taking agood polish, and retaining its brightly polished surface for aconsiderable period of time.

By comparative tests I find that contact points made of my new metalcomposition, retain their efficiency for substantially the same time asdo platinum points, under normal loads, while under overload conditionsmy composition seems to be superior, to platinum, being capable ofcarrying-greater currents and withstanding the arcing set up by thepassage of heavy currents with less disastrous effects than theplatinum.

While I have described in considerable detail one specific process ofmanufacturing my new metal composition, together with the preferredconstituents entering into the same, and one particular use to which mycomposition seems to be peculiarly fitted, it will be understood that myinvention is not to be regarded as limited to these details, except inso far as such limitations are ineluded within the terms of. thefollowing claims, in which it is my intention to claim all noveltyinherent in my invention, as

broadly as is permissible, in view of the 1. A contact point for makingand break;

ing electrical circuits and comprising a metal composition includingupward of 70 per cent. of nickel and upward of 3 per cent. of uncombinedcarbon.

2. A contact point for making and breaking electrical circuits andformed of a metal composition comprisin substantially ure nickel,carrying upwar of 3 per cent. 0 uncombined carbon.

3. A cast metal contact point for making and breaking electricalcircuits and comprising upward of 70 'per cent. of nickel and upwardof 3per cent. of graphitic carbon.

4. A cast metal contact point for making and breaking electricalcircuits and comprising substantlally pure nickel, carrying up- HENRY K.SANDELL.

